X-Ray Rounds Cass Djurfors Feb 20, 2003

10 y.o. boy with leg pain Obese 10-year old male presents with a two week history of right thigh and knee pain. He states that the pain is mainly in his thigh (points to his upper thigh) but radiates down to his knee.

10 y.o. boy with leg pain He was playing basketball when he collided with another player and fell. He noted severe pain in his thigh and had to limp home, mostly on his left leg. The pain is worse with weight-bearing and much better when lying in bed. No history of fever, rash, chest discomfort, or pains in other joints.

On Exam… Vitals: –T37.0 (oral) –P66 –R20 –BP 112/65 –weight 69.3 kg (>>95th percentile) –height 152 cm (>95th percentile) Alert, cooperative, in no distress Head and neck, CVS, Respiratory and Abdominal exam all normal

On Exam… Right lower extremity: –Moderate tenderness in the upper anterior thigh –Severely tender in the hip, ROM not done –Pubic symphysis, mid thigh, knee, tibia/fibula all non tender –No joint swelling –ROM knee normal Left lower extremity: –Non-tender, normal exam

And the answer is…SCFE! Hip radiographs show a slipped capital femoral epiphysis on the right Left hip appears normal (but difficult to rule out an early slip)

SCFE The radiographic diagnosis of slipped capital femoral epiphysis (SCFE) can be subtle In this case, the physis appears to be wider and more lucent in the patient's right hip compared to his left The position of the femoral head epiphysis should resemble a cap over the physis Subtle cases may just show a slight malpositioning of the epiphysis

Klein line: a line drawn along the superior border of the proximal femoral metaphysis should intersect part of the proximal femoral epiphysis In this patient, right hip shows the line just touching the lateral margin of the epiphysis… this is abnormal and indicates that the femoral capital epiphysis has slipped inferiorly and medially The patient's normal left hip shows the line intersecting the lateral part of the femoral epiphysis

Management Patient is hospitalized and put on bedrest He is taken to the operating room for internal fixation of his right capital femoral epiphysis.

Much more obvious:

Severe left slipped capital femoral epiphysis The slipped capital femoral epiphysis on the right is not as obvious This patient has bilateral SCFE, severe on the left, and moderate on the right

SCFE Presents with acute, subacute, or chronic pain in the hip, thigh, or knee Ambulatory ability may range from non- weight bearing to a normal gait Most comfortable with hip externally rotated Unable to fully internally rotate affected hip

SCFE Occurs during adolescent growth spurt Most frequent in obese children 40-80% are bilateral Classification emphasizes epiphyseal stability –Stable=ambulation possible –Unstable=ambulation impossible…do not attempt passive ROM on exam for fear of further slip –Mild/Mod/Severe: 1/3, ½, >1/2 90% are stable: good prognosis if diagnosed early Unstable SCFE has a much poorer prognosis due to high risk of avascular necrosis

Diagnosis SCFE can be detected radiographically in most instances AP views show only inferior and medial slips Early slips tend to be posterior…best seen on lateral x-ray CT scanning can be helpful, but is not usually needed in the emergency department Obvious cases are hard to miss

Diagnosis Subtle cases: –Widened or irregular epiphyseal plate (compare to opposite side) –The physis may alternatively appear thinner than the normal side (esp with posterior slips) –A line drawn along the superior border of the metaphysis (the Klein line) will intersect less of the epiphysis compared to the normal side –The “blanch sign of Steel” (AP view): crescent- shaped area of increased density represents superimposition of the posteriorly displaced epiphysis on the femoral neck

Treatment Ensure child is non weight-bearing Orthopedic referral Most are fixed with a single central screw

Lateral view showing an early slipped capital femoral epiphysis. Note the subtle posterior step-off of the epiphysis on the metaphysis at the physeal level (arrow).

Klein's line, the line along the superior aspect of the femoral neck. (Left) In the normal hip, the superior border of the epiphysis projects superiorly to Klein's line. (Right) In a hip with an early slipped capital femoral epiphysis, the superior border of the epiphysis lies on Klein's line. In more advanced cases, the epiphysis projects inferiorly to it. Note the metaphyseal blanch sign of Steel (arrow).